1. Field
The present invention relates to a digital camera having facilities which detect a main object such as a person from through image data, that is, image data obtained by thinning-out reading from an image pickup device to provide a moving image for view finder to a user, and provide information related to the detected object for a process to realize shooting support facility such as automatic focusing (AF) control.
2. Description of the Related Art
As shooting support facilities for a digital camera a digital camera, a technique of controlling an automatic focusing (AF) control mechanism on the basis of an image obtained from a preset expected subject area or an area designated by the user operating a button or the like provided on an operating panel is proposed.
Moreover, a technique of analyzing through image data acquired in the process of composing a shot by the user before shooting and thereby detecting an area having a feature of an image representing a human face, and focusing on the human face detected as a subject on the basis of image data of the detected area, is proposed and practically used.
By using this face detecting technique, it is possible to securely focus on a subject irrespective of whether there is a main object in a focus adjusting area provided in advance at the center of a frame or the like. Thus, shooting in a free composition can be realized.
Meanwhile, a technique of extracting a featuring point of a human face from a shot image and identifying an individual face obtained as a subject in the shot image on the basis of the degree of matching with a featuring point of a registered person, is proposed (Japanese Unexamined Patent Application Publication No. Hei-6-259534).
Note that, as image pickup devices provided in digital cameras have an increasing number of pixels, the image quality of shot images is significantly improved. For example, even when a part of a shot image is enlarged in playback, the image has sufficiently high quality that can be viewed clearly.
As one of the facilities to utilize such good image quality of the digital camera, a facility is provided which enables a liquid crystal display section provided in the digital camera or a projector connected to the digital camera via a cable to enlarge a desired part of a shot image in display.
To deal with such enlarged display facilities, in the digital camera in which AF control is carried out on the basis of an image in an expected subject area or a user-designated area as described above, information indicating the expected subject area or the designated area is recorded to a storage medium together with the shot static image (hereinafter referred to as a shot image), a thumbnail image corresponding to this shot image, tag data related to the shooting date and time and so on (Japanese Unexamined Patent Application Publication No. 2004-193977 and No. 2003-125251). As the information related to the expected subject area or the designated area is thus recorded in association with the shot image as a part of the information related to the shooting, linking to the enlarged display facilities after shooting is realized.
Meanwhile, the above-described technique of Japanese Unexamined Patent Application Publication No. 2004-193977 assumes that a main object is captured in the expected subject area, as an image to be shot. Therefore, for example, it cannot deal with a case of capturing the object in the expected subject area, then half-pressing the shutter button to focus, and then shooting an off-center subject. The technique of Japanese Unexamined Patent Application Publication No. 2003-125251 enables execution of AF control for a designated area located at a desired position. To this end, however, the user must operate the AF cursor to decide the designated area during shooting.
On the other hand, in the digital camera employing the face detecting technique, secure AF control can be carried out wherever in a frame the face of a person is located. Therefore, satisfactory shooting can be carried out with a composition having an extremely high degree of freedom and without performing complicated operations.
However, in the related art, the information acquired by face detection is provided exclusively for a shooting process such as AF control. No linking is made with facilities prepared for the processes after the acquisition of the shot image (for example, slide-show facilities including the above-described enlarged display facility).
Note that, as the capacity of the storage medium for storing the image is increased, the number of images shot by the user of the typical digital camera increases very much.
Therefore, for example, a technique of automatically filing a large number of shot images on the basis of various viewpoints, such as filing by each shot object, in addition to the shooting date and time, is demanded.
For example, if the above-described face detecting and recognizing technique is applied to shot images, it is possible to extract images in which each object is captured. It is thus possible to selectively take or leave shot images depending on whether a desired object is captured in the images, and to file the shot images by each object.
However, since the image data shot by the recent digital camera is of an extremely large volume, as described above, detecting an area corresponding to a human face in a shot image requires longer amount of time corresponding to increasing the number of pixels in the shot image.